The risk of coronary heart disease (CHD) can be diminished significantly by the modification of dietary intakes and the cessation of smoking. A reduction of saturated fat intake and an increase in plant foods has both been associated with beneficial effects on serum cholesterol, hypertension, atherosclerosis and mortality. These dietary and lifestyle modifications are hypothesized to act by increasing antioxidant protection and reducing oxidative damage. Such damage is a primary mechanism in the development of atherosclerosis, as demonstrated by numerous basic science studies and suggested by several small human feeding trials. Specific oxidatively modified macromolecules have been found in advanced atherosclerotic lesions. However, no information is available on the early time course of oxidative damage in human subjects. The investigators propose to measure oxidation products from several classes of compounds, thereby studying multiple pathways in atherogenesis, and serum antioxidants. They will study a cohort of about 3500 black and white young men and women. Between June, 2000 and June, 2001 (15 years after baseline), CARDIA participants will be assessed for subclinical CHD by the measurement of coronary calcification at the earliest stages of detectability. In addition, endothelial dysfunction will be assessed by measurement of plasma adhesion molecules and microalbuminuria. By measuring several kinds of antioxidants and assessing oxidative damage in classes of compounds, this project will test the association of oxidative damage and early/subclinical CHD. In addition, utilizing the extensive biochemical and sociodemographic data collected over the first 15 years of CARDIA, they will define the confounding effects of traditional CHD risk factors. The investigators state that the analyses will allow testing several major hypotheses about the early evolution atherosclerosis and CHD. They further state that the conclusions will identify new strategies for the prevention of CHD.